Remote data logging systems which monitor physical properties such as temperature or relative humidity over extended periods of time are well known in the art. Such systems usually consist of a plurality of data loggers and a host computer. Each data logger is configured for its mission while connected to the host computer. After being configured, the logger is disconnected from the host and placed in its monitoring site, e.g., placed in a crate of fruit to monitor temperature at predetermined intervals during transit. After the mission is complete, the logger is reconnected to the host and the logger's data is downloaded to the host.
There are two variations on the basic data logger design which are also known in the art. One variation is the "event logger." Event loggers are designed to record data during a relatively short event, such as an earthquake, while conserving available memory and power during the periods between events. An earthquake event logger samples and records high resolution data during the quake, but samples and records little or no data before and after the quake. The other variation is the "pulse recorder." Pulse recorders count pulses over a given period of time. Data is then provided in the form of pulses per period. Pulse recorders are useful in connection with devices such as Geiger counters. The basic data logger design and these two variations allow a great variety of monitoring tasks to be carried out. Nevertheless, there are a number of other monitoring tasks which people are interested in, and for which no practical data logging device is available.